[LayoutNG] Move remaining ng_units structs to their own files

third_party/WebKit/Source/core/layout/ng/geometry/ng_box_strut.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/layout/ng/geometry/ng_box_strut.h"
+
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+
+bool NGBoxStrut::IsEmpty() const {
+  return *this == NGBoxStrut();
+}
+
+bool NGBoxStrut::operator==(const NGBoxStrut& other) const {
+  return std::tie(other.inline_start, other.inline_end, other.block_start,
+                  other.block_end) ==
+         std::tie(inline_start, inline_end, block_start, block_end);
+}
+
+// Converts physical dimensions to logical ones per
+// https://drafts.csswg.org/css-writing-modes-3/#logical-to-physical
+NGBoxStrut NGPhysicalBoxStrut::ConvertToLogical(NGWritingMode writing_mode,
+                                                TextDirection direction) const {
+  NGBoxStrut strut;
+  switch (writing_mode) {
+    case kHorizontalTopBottom:
+      strut = {left, right, top, bottom};
+      break;
+    case kVerticalRightLeft:
+    case kSidewaysRightLeft:
+      strut = {top, bottom, right, left};
+      break;
+    case kVerticalLeftRight:
+      strut = {top, bottom, left, right};
+      break;
+    case kSidewaysLeftRight:
+      strut = {bottom, top, left, right};
+      break;
+  }
+  if (direction == TextDirection::kRtl)
+    std::swap(strut.inline_start, strut.inline_end);
+  return strut;
+}
+
+String NGBoxStrut::ToString() const {
+  return String::format("Inline: (%d %d) Block: (%d %d)", inline_start.toInt(),
+                        inline_end.toInt(), block_start.toInt(),
+                        block_end.toInt());
+}
+
+std::ostream& operator<<(std::ostream& stream, const NGBoxStrut& value) {
+  return stream << value.ToString();
+}
+
+}  // namespace blink